KR20110070036A - A photoelectric conversion module using an interposer - Google Patents

Abstract

PURPOSE: A photoelectric transforming module using an interposer is provided to enhance a photo-coupling between an optical device and an optical waveguide by using a conventionally used optical device. CONSTITUTION: A substrate(210) includes a wall pad(212). A driving circuit chip(220) is installed on an upper part of the substrate. An optical device(240) is electrically connected to the wall pad. An interposer includes the first electrode pad and the second electrode pad. The first electrode pad is formed on the first surface of the interposer in correspondence with a position of the wall pad. The second electrode pad is formed on the second surface positioned contrary to the first surface and is electrically connected to the first electrode pad through a via hole. When the first electrode pad is electrically connected to the wall pad and the second electrode pad is electrically connected to an electrode for external connection, the interposer electrically connects the driving circuit chip to the optical device.

Description

Photoelectric conversion module using interposer {A PHOTOELECTRIC CONVERSION MODULE USING AN INTERPOSER}

The present invention relates to a photoelectric conversion module for facilitating optical coupling between an optical element and an optical waveguide, and more particularly, to a photoelectric conversion module using an interposer that can facilitate electrical connection between the optical element and the driving IC. will be.

Recently, information and communication technology has tended to increase the speed and capacity of data to be transmitted. Accordingly, development of optical communication technology for realizing a high-speed communication environment has been actively conducted. In general, optical communication converts an electrical signal into an optical signal in a photoelectric conversion element on a transmitting side, transmits the converted optical signal to a receiving side using an optical fiber or an optical waveguide, and receives the optical signal received in the photoelectric conversion element on the receiving side. Converts back to an electrical signal. In order for such a photoelectric conversion element to be applied and commercialized in a system, electrical connection and optical coupling must be configured to be effective.

1 is a cross-sectional view showing an example of a photoelectric conversion module proposed by NTT in Japan. As shown in FIG. 1, on the printed circuit board (PCB) 10, the driving IC chip 20 on which the optical device 30 is mounted is formed by solder balls 23. It is joined.

The printed circuit board 10 and the driving IC chip 20 mounted with the optical device 30 are aligned and bonded by alignment means (for example, alignment balls) formed on the printed circuit board. Through such alignment, light generated from the optical device 30 may be incident to the optical waveguide 15 of the printed circuit board 10.

The optical device 30 may be a light emitting device or a light receiving device, and in the case of a light emitting device, a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED) may be used. In the case of a light receiving device, a photodetecting device may be used.

In the conventional photoelectric conversion module configured as described above, the optical device 30 is driven in accordance with a control signal generated from the driving IC chip 20, and the optical device 30 converts an electrical signal into an optical signal and outputs the optical signal. . The optical signal output from the optical element 30 is reflected through the micromirror 16 inclined at a specific angle (for example, 45 °) formed at one end surface of the optical waveguide 15 of the printed circuit board 10 The inside of the waveguide 15 is advanced. However, in order to form a mirror with an inclination of 45 ° at the end of the optical waveguide 15, a cutting process and a reflective film coating process are additionally required, and the conventional photoelectric conversion module having such a configuration drives the photon 30 to drive the IC chip. There is no problem in the electrical connection between the 20 and the printed circuit board 10, but there are many problems in the optical connection (or optical coupling) between the optical element 30 and the optical waveguide 15 of the printed circuit board.

That is, the conventional photoelectric conversion module has a disadvantage in that the optical coupling efficiency is very low due to the mutually spaced distance between the optical device 30 and the optical waveguide 15. For example, in the case of using the VCSEL as the optical device 30, the VCSEL has a diverging angle of about 25 degrees to about 30 degrees when emitting light in the air, so that the distance from the optical waveguide 15 becomes long. As the optical coupling efficiency decreases significantly.

In addition, a method has been proposed to improve optical coupling efficiency by installing a lens between the optical device 30 and the optical waveguide 15 according to the separation distance between the photoelectric conversion module and the optical waveguide. An additional process for installing between the optical waveguide 15 and the optical waveguide 15 is required, which is an obstacle to mass production.

As described above, the conventional photoelectric conversion module uses not only a lot of time and cost for optical alignment between the optical element and the optical waveguide on the PCB, but also uses expensive square ratio and optical materials (lenses, mirrors, coatings). In addition, the optical coupling loss was also very high, more than 3dB.

2 is a cross-sectional view of the photoelectric conversion module 100 previously filed by the applicant. As shown in FIG. 2, the photoelectric conversion module 100 according to the present invention includes a plurality of semi-cylindrical shapes connected to the plurality of electrode lines 111 and at least a portion of the plurality of electrode lines 111 from the side of the substrate. A substrate 110 including two wall pads 112 and a driving circuit chip 120 electrically bonded to at least a portion of the plurality of electrode lines 111 of the substrate 110 on the substrate 100. And an optical element (light receiving and light emitting element) 140 electrically connected to the wall pad 112 formed on the side surface of the substrate 110.

According to the above-described configuration of FIG. 2, the optical device is formed on the side surface of the substrate 100 using the wall pad in the substrate 100, so that the lens, the mirror, and the optical device and the optical waveguide between the optical device and the optical waveguide are fine as in the related art. The light can be transmitted to the optical waveguide 150 positioned at the rear end without adjusting the position, so that the optical loss can be greatly reduced, and as a result, the mass production and the low price are realized.

In the configuration of the photoelectric conversion module 100 as described above, as shown in FIG. 3A, in the electrode of the optical device 140, the electrode 143a is disposed in the opposite direction of the light emitting portion or the light receiving portion 142a. Positioned optical devices (bottom emitting VCESL (or bottom absorption PD)) must be used. However, in a conventionally used optical element, as shown in Fig. 3B, the position of the electrode 143b and the position of the light emitting portion or the light receiving portion 142b are located on the same surface of the substrate 141b for the optical element. Since it is a top emitting VCESL (or top absorption PD), in order to implement the photoelectric conversion module 100 shown in FIG. 2, as shown in FIG. It is necessary to use a special optical element located in the opposite direction of the light emitting unit or the light receiving unit 142a. This special optical element has a poor optical characteristic, and a new problem is very expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a photoelectric conversion module having improved optical coupling characteristics between an optical device and an optical waveguide, and an optical device commonly used as an optical device. The present invention provides a photoelectric conversion module employing emitting VCESL (or top absorption PD).

The present invention provides a photoelectric conversion module having a structure in which the ends of the optical waveguide face each other in order to solve the above problems, and at the same time using an interposer (top emitting VCESL or top absorption PD) It provides a photoelectric conversion module employing.

Specifically, according to the first aspect of the present invention, a photoelectric conversion module comprising a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side of the substrate. An interposer for use in an interposer, wherein the interposer is a first electrode pad formed on a first surface of the interposer corresponding to a position of a wall pad formed on a side of the substrate, and an opposite surface of the first surface. A second electrode pad formed on a second surface and electrically connected to the first electrode pad through a via hole, wherein the interposer includes: the first electrode pad being electrically connected to the wall pad; When the electrode pad is electrically connected to the external connection electrode of the optical device, it characterized in that to provide an electrical connection between the drive circuit chip and the optical device It provides an interposer.

According to a second aspect of the present invention, there is provided a photoelectric conversion module including a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side surface of the substrate. An interposer for use in an interposer, wherein the interposer includes a groove portion formed in a first surface of the interposer and a hole formed through a central portion of the groove portion for mounting the optical device, and the interposer includes the substrate. A first electrode pad formed at a periphery of the groove portion of the interposer, and a position formed in the groove portion corresponding to a position of an electrode of an optical element mounted in the groove portion, corresponding to a position of a wall pad formed at a side surface of the interposer; A second electrode pad internally connected to an electrode pad, wherein the interposer includes: the first electrode pad electrically connected to the wall pad; And, when the second electrode pad is electrically connected to an external connection electrode of the optical device, provides an electrical connection between the driving circuit chip and the optical device. To provide.

According to a third aspect of the present invention, there is provided a photoelectric conversion module including a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side of the substrate. The photoelectric conversion module further includes an interposer electrically connected between the wall pad and the optical device, wherein the optical device includes an electrode for electrical connection to the outside and a light emitting part formed on the same surface as the electrode. Or a light receiving unit, wherein the interposer is provided to convert the positions of the electrodes and the light emitting unit or the light receiving unit formed on the same surface of the optical device in opposite directions to each other.

Here, the interposer has the same features as the features described in the first and second aspects described above.

According to the present invention described above, it is possible to implement a photoelectric conversion module that facilitates optical coupling between the optical element and the optical waveguide, and also facilitates electrical connection between the optical element and the driving circuit chip. In particular, since the optical element and the optical waveguide face each other, the optical coupling is easy, and there is no need for a separate optical device. .

On the other hand, since ordinary optical devices (light emitting devices and light receiving devices) generally used are in the form of a device (top emitting VCESL or top absorption PD) in which the position of the electrode coincides with the direction in which light is emitted (or received), Conventional photoelectric conversion module using a wall pad (Wall Pad) had to use a special device that is the opposite of the position of the electrode and the position where light is emitted or received, but using the interposer according to the present invention is usually used The direction of the device electrode can be changed in the direction opposite to the direction of the light emitting (or light-receiving) part, and the electrical connection between the driving circuit chip and the optical device is easily solved.

According to the present invention, it is possible to implement a photoelectric conversion module capable of optical coupling in a form in which an optical device and an optical waveguide face each other using a normal optical device (top emitting VCESL or top absorption PD), thereby lowering the cost of the photoelectric conversion module. Optical coupling efficiency is always possible, simplifying the structure.

Hereinafter, a photoelectric conversion module of the present invention and a manufacturing method thereof will be described with reference to the accompanying drawings. In addition, in the description of the present invention, detailed description of the known technology related to the present invention will be omitted.

(First embodiment)

4 is a diagram illustrating a first embodiment of the photoelectric conversion module 200 according to the present invention. The photoelectric conversion module 200 according to the first embodiment of the present invention includes a plurality of semi-cylindrical walls connected to a plurality of electrode lines 211 and at least a portion of the plurality of electrode lines 211 at the side of the substrate. A substrate 210 including a pad 212, a driving circuit chip 220 electrically bonded to at least a portion of the plurality of electrode lines 211 of the substrate 210 on the substrate 210; An interposer electrically connected to the wall pad 212 formed on the side surface of the substrate 210 is electrically connected through the solder ball 223. In addition, on the interposer 230, an optical element (top emitting VCESL (or top absorption PD)) having the same position as the electrode and the light emitting portion or the light receiving portion as described above is provided. The wall pad 212 formed on the sidewall of the substrate 210 may be formed by forming conductive vias in the substrate 210 and cutting the conductive vias in a direction perpendicular to the substrate.

FIG. 5 illustrates the electrical coupling between the interposer 230 and the optical device 240 (where the optical device is a top emitting VCESL or a top absorption PD) shown in FIG. 4.

In general, when the interposer 230 is not used, as shown in FIG. 3A, an optical device having an opposite position between the electrode 143a and the light receiving unit or the light emitting unit 142a should be used. As shown in FIG. 3B, when using a conventional optical device having the same positions of the electrode 143b and the light receiving portion or the light emitting portion 142b, the position of the electrode and the wall pad on the side of the substrate must be reversed. It may be electrically connected to perform a predetermined function.

In the present invention, the position of the electrode formed on the optical device using the interposer 230 is replaced with the one formed on the opposite surface. The interposer 230 is a type of PCB substrate used for electrical connection between the optical device 240 and the side wall pad 212 of the substrate (see FIG. 4). The first surface Sa and the second surface Sb of the interposer 230 are electrically connected to the first and second electrode pads 231 and 233 disposed on the respective surfaces through the via holes 232, respectively. In addition, the first electrode pad 231 formed on the first surface Sa of the interposer is electrically connected to the wall pad 212 formed on the sidewall of the substrate 210 (see FIG. 4) through the solder ball 223. The second electrode pad 233 formed on the second surface Sb of the interposer is electrically connected to the electrode 243 of the optical device 240 installed above the interposer 230 through the bonding wire 244. do. Also, in order to protect the wire bonding between the second electrode pad 233 of the interposer and the electrode 243 of the optical device 240, the exposed portion of the interposer 230 and the optical device 240 are provided. Molding using a transparent resin 245 to surround the exposed portion of the.

Accordingly, by the function of the interposer 230, even if the electrode and the light emitting portion or the light receiving portion is a conventional optical element formed on the same surface, the light waveguide or the waveguide is electrically connected to the wall pad formed on the side of the substrate and connected to the rear end. It can receive light from.

(2nd Example)

Hereinafter, a second embodiment of the present invention will be described. The first embodiment described above describes the structure in which the interposer 230 and the optical device 240 are coupled by wire bonding, whereas the second embodiment of the present invention is an optical device capable of flip chip bonding. It is suitable for constructing a photoelectric conversion module using (light emitting element and light receiving element).

In order to help the understanding of the present invention and to avoid duplicate description, the same reference numerals as mentioned above are given to the overlapped configuration in the first embodiment, particularly the configuration related to the substrate 210 and the driving circuit chip 220. This will be described below.

6 is a view showing a second embodiment of the photoelectric conversion module 300 according to the present invention. The photoelectric conversion module 300 according to the second embodiment of the present invention may include a plurality of walls having a semi-cylindrical shape connected to a plurality of electrode lines 211 and at least a portion of the plurality of electrode lines 211 at the side of the substrate. A substrate 210 including a pad 212, a driving circuit chip 220 electrically bonded to at least a portion of the plurality of electrode lines 211 of the substrate 210 on the substrate 210; The interposer 330 electrically connected to the wall pad 212 formed on the side surface of the substrate 210 is electrically connected through the solder ball 223.

In addition, the interposer 330 is provided with an optical element (top emitting VCESL (or top absorption PD)) having the same position as the electrode and the light emitting portion or the light receiving portion as described above. The wall pad 212 formed on the sidewall of the substrate 210 may be formed by forming conductive vias in the substrate 210 and cutting the conductive vias in a direction perpendicular to the substrate.

FIG. 7 illustrates the electrical coupling between the interposer 330 and the optical device 340 illustrated in FIG. 6, wherein the optical device is a top emitting VCESL or a top absorption PD.

First, in order to electrically connect the interposer 330 and the optical device 340 through flip chip bonding, the cavity or the groove 338 in which the optical device 340 is to be mounted on the multilayer PCB to be used as the interposer 330. Is formed. Further, in the center portion of the groove portion 338, the hole 337 is arranged so that the light to the light receiving portion of the optical element 340 or from the light emitting portion 342 is aligned with an optical waveguide (not shown) positioned in the advancing direction of the light at the rear end. To form.

Next, the electrical connection between the side wall pad 212, the interposer 330, and the optical device 340 of the substrate 210 will be described. As in the first embodiment, it should be noted that the optical device 340 used in the second embodiment uses an optical device (top emitting VCESL (or top absorption PD)) having the same position as the electrode and the light emitting portion or the light receiving portion. .

First, a first electrode pad 333 is formed in the groove 338 of the interposer 330 to correspond to the position of the electrode 343 of the optical device 340, and surrounds the groove 338. The second electrode pad 331 is formed at the outer edge of the substrate in correspondence with the position of the wall pad 212 of the substrate. The electrode 343 of the optical device 340 is connected to the first electrode pad 333 and the solder ball 344 of the interposer 330 by flip chip bonding, and the second electrode pad 331 is formed on the same surface. Is electrically connected to the wall pad 212 of the substrate 210 by a flip chip bonding method through the solder ball 223. In addition, the first electrode pad 333 and the second electrode pad 331 of the interposer 330 may be electrically connected to each other through an electrical connection means 332 (for example, a wire) to form a substrate 210 (specifically, a substrate). The signal from the driving circuit chip mounted at 210 may be transmitted to the optical device 340.

Also, although not shown, the transparent resin 245 may be molded on the surface opposite to the surface on which the electrode pad of the interposer is formed, including the exposed portion of the interposer and the holes 337.

Although the first and second embodiments of the present invention have been described above, the present invention is not limited thereto, and in a conventional optical device in which the electrodes and the light receiving portion or the light emitting portion of the optical element are the same, the electrode, the light receiving portion, or the light emitting portion Any structure that can reverse the positional relationship can be employed.

(Optical transmission system)

FIG. 8 illustrates an optical waveguide 1500 (or an optical fiber or an optical fiber) of the photoelectric conversion modules 1200 and 1300 (not shown in FIG. 8, but the present invention is not limited thereto) of the first or second embodiment described above. FIG. Is a diagram schematically illustrating a configuration of an optical transmission / reception system 1000 connected by an optical PCB having a waveguide embedded therein.

In the first photoelectric conversion module 1200, a plurality of electrode lines 1211 are formed, a plurality of wall pads 1212 having a semi-cylindrical shape are formed on a side thereof, and the plurality of wall pads 1212 are formed. A first driving circuit chip each electrically connected to electrode lines on the first substrate 1210 and the first substrate 1210 connected to some of the plurality of electrode lines; 1220 and a first optical device (here, the first interposer 1230, which provides an electrical connection between the wall pad 1212 formed on the side of the first substrate 1210). The first interposer 1230 has a configuration substantially the same as that of the interposer 230 of the first embodiment and the interposer 330 of the second embodiment shown in FIGS. 5 and 7 described above. Description is omitted.

Also, in the second photoelectric conversion module 1300, the second optical device mounted on the second interposer 1330 receives the light transmitted through the optical waveguide 1500 from the light emitting device 1240 which is the first optical device. Except for the light receiving element 1340, the same structure as that of the first photoelectric conversion module 1200 may be omitted.

An optical PCB 1500 including an optical waveguide, an optical fiber, and an optical waveguide (or optical fiber) is typically formed between the light emitting device 1240 and the light receiving device 1340, and the first photoelectric conversion module 1200 may be provided. The second photoelectric conversion module 1300 may be bonded to the main board 1100.

In the optical transmission / reception system 1000 configured as described above, when a data signal is input to the first driving circuit chip 1220 positioned above the first photoelectric conversion module 1200, the first driving circuit chip 1220 is driven. A signal is output, and the output driving signal is transmitted to the light emitting device 1240 through the wall pads 1212 and the first interposer 1230 of the first substrate 1210.

The light emitting device 1240 emits light based on a driving signal of the first driving circuit chip 1220, and the light emitted from the light emitting device 1240 is aligned with the light emitting device 1240. The second substrate 1310 through the second interposer 1330 received by the light receiving device 1340 of the second photoelectric conversion module 1300 through the waveguide 1500 and electrically connected to the light receiving device 1340. The data is inputted to the second driving circuit chip 1320 or the receiving circuit chip via the wall pad 1312.

According to the present invention as described above, the first photoelectric conversion module 1200 and the second photoelectric conversion module 1300 by using the interposer, the electrode pad and the light receiving unit or a conventional optical device located on the same surface without deteriorating the light efficiency. The optical signal may be converted into an electrical signal or an electrical signal may be converted into an optical signal.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a view showing an example of a conventional photoelectric conversion module.

2 shows an example of a photoelectric conversion module when no interposer is used.

FIG. 3A illustrates an optical device in which a light receiving unit or a light emitting unit and an external connection electrode are formed on opposite surfaces thereof, and (b) is a light source in which a light receiving unit or a light emitting unit and an external connection electrode are formed on the same surface. Exemplary drawing of a ruler.

4 is a view showing a photoelectric conversion module according to a first embodiment of the present invention.

FIG. 5 illustrates the interposer used in FIG. 4 in more detail.

6 is a view showing a photoelectric conversion module according to a second embodiment of the present invention.

FIG. 7 illustrates the interposer used in FIG. 7 in more detail.

8 is a view showing an optical transmission and reception system constructed using a plurality of photoelectric conversion modules using an interposer according to the present invention.

Claims (7)

An interposer for use in a photoelectric conversion module comprising a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side of the substrate. The interposer is formed on a first electrode pad formed on a first surface of the interposer and a second surface opposite to the first surface corresponding to a position of a wall pad formed on a side surface of the substrate. A second electrode pad electrically connected to the electrode pad through a via hole, The interposer may be electrically connected between the driving circuit chip and the optical device when the first electrode pad is electrically connected to the wall pad and the second electrode pad is electrically connected to an external connection electrode of the optical device. Interposer providing a connection. An interposer for use in a photoelectric conversion module comprising a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side of the substrate. The interposer includes a groove formed in the first surface of the interposer and a hole formed through the central portion of the groove for mounting the optical device, The interposer surrounds the groove portion of the interposer in response to the position of the first electrode pad formed in the groove portion and the wall pad formed on the side surface of the substrate, corresponding to the position of the electrode of the optical element mounted in the groove portion. A second electrode pad formed at a periphery and internally connected to the first electrode pad; The interposer may be electrically connected between the driving circuit chip and the optical device when the second electrode pad is electrically connected to the wall pad and the first electrode pad is electrically connected to an external connection electrode of the optical device. An interposer for use in a photoelectric conversion module characterized by providing a connection. The method of claim 1, And the second electrode pad of the interposer and the electrode of the optical device are electrically connected through wire bonding. The method of claim 2, And the first electrode pad of the interposer and the electrode of the optical device are electrically connected through flip chip bonding. The method according to claim 3 or 4, An interposer for use in a photoelectric conversion module, wherein the external connection electrode of the optical element and the light emitting portion or the light receiving portion of the optical element are formed on the same surface. The method of claim 5, The optical device is an interposer for use in a photoelectric conversion module, characterized in that one of a top emitting VCESL (top emitting VCESL) or a top absorption photodiode (top absorption PD). A photoelectric conversion module comprising a substrate including a wall pad, a driving circuit chip mounted on an upper portion of the substrate, and an optical element for electrically connecting to a wall pad formed on a side surface of the substrate. The photoelectric conversion module further includes an interposer electrically connected between the wall pad and the optical device. The optical device includes an electrode for electrical connection to the outside, a light emitting portion or a light receiving portion formed on the same surface as the electrode, The interposer is a photoelectric conversion module, characterized in that for converting the position of the electrode and the light emitting portion or the light receiving portion formed on the same surface of the optical device in the opposite direction.

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